In a DC (direct current)/DC power converter, such as e.g. a charge pump circuit, an input voltage may be transformed into a specified output voltage with the help of a plurality of switching elements and at least one capacitor for temporarily storing an electrical charge. At the same time, the input voltage is typically used to control circuitry for controlling the switching behavior of the plurality of switching elements. Said control circuitry may e.g. include driver circuits for driving the gate voltages of said transistors. In case of an overvoltage or overcurrent at the input of the charge pump, both the driver circuits as well as the transistors themselves may be damaged if the driver circuits or the transistors are not designed to withstand high input voltages or currents. As a remedy, one may use driver circuits and transistors which are robust against high input voltages and currents. However, this may result e.g. in a decreased power conversion efficiency or in an increased total area required for implementing the charge pump compared to scenarios where e.g. low voltage components are used.
Several techniques of protecting a charge pump from an overcurrent and/or overvoltage at its input have been presented in the literature. For example, methods of linear voltage regulation have been suggested at the input of a charge pump. By adding a linear regulator (such as e.g. a low-dropout LDO regulator) at the input of a charge pump, the input voltage is dropped (or regulated) before a charge pump divides the dropped voltage to one half for output. However, a power device for the linear regulation must be added in series on the current path of a charge pump. And that additional power device may take significant die area and burn extra power even in the case that the charge pump is switching for voltage division without using the protection/regulation function implemented by the additional linear regulator.